Cutting knife control mechanism for sewing machines and the like



Jan. 22, 1963 "H. GROSS ETA'L 3,074,363

CUTTING KNIFE CONTROL MECHANISM FOR SEWING MACHINES AND THE LIKE Filed March 29, 1961 /-v/vro2 45 43 HELMUT GROSS KARL KLEEMANN 5 Y United States Patent 3,074,363 CUTTIYG KNIFE CONTROL MECHANISM FOR SEWING MACHHNES AND THE LIKE Helmut Gross and Karl Kleemann, Kaiserslautcrn, Pfalz,

Germany, assignors to G. M. Pfafi A,G., Kaiser-slantern, Pfalz, Germany, a corporation of Germany *iled Mar. 29, 1961, Ser. No. 99,274 Clmhns priority, application Germany Apr. 4, 1960 15 Claims. (Cl. 112-125) The present invention relates to mechanism for controlling the cutting knife of a sewing machine or the like reciprocating operating member driven from a continuous ly rotating drive shaft through a motion-transmitting system or linkage adapted to convert the rotary motion of said shaft into reciprocating motion of said knife or other driven member.

An important object of the invention is the provision of an improved control mechanism of this type for starting and stopping the operation of the cutting knife or other driven member safely and smoothly without interruption of the rotation and independently of the speed of the driving shaft or member.

While in the following the invention will be described with specific reference to the operation of the material cutting knife of a sewing machine for the trimming or cutting of the work or sewing material during the operation of the machine, it will become apparent that the improved control and operating device shown and disclosed herein may be employed with equal advantage in connection with the operation of other reciprocating devices driven from a continuously operating drive shaft or member.

In its specific embodiment, the invention relates to a material cutting or trimming device for sewing machines comprising a reciprocating cutting knife bar or carrier driven by the arm or drive shaft of the machine through a knuckle joint linkage, wherein in order to stop the operation of and to retract the cutting knife from its operative position to its inoperative position the knuckle joint is operated manually by means of a control lever or the like to a position in which the joint axis coincides with the fixed axis of an oscillating driving lever operatively connected to the drive shaft, on the one hand, and being rot-atively connected to one of the component arms or links of said joint. As a consequence, the oscillating movement imparted by said lever to said joint and, in turn, to the knife or other driven member may be reduced to zero smoothly and without interruption of the rotation of the driving shaft, in such a manner as to enable the stoppage of the knife operation instantly and expedis tiously, while at the same time retracting the knife from its operative position to an inoperative position spaced from the work or sewing material. being operated on by the machine.

According to a known arrangement of this type, the knuckle joint provided in the motion-transmitting path between the driving member and the cutting knife holder or carrier forms a linkage system which has a pair of rotary or pivot axes, one of said axes being adjustable by means of a common control lever for the operation of said knife between an operative and inoperative position and the other of said axes being adjustable for varying the operating stroke of said knife. Inasmuch as such a device has no stationary or fixed axis about which the system is allowed to oscillate, it inherently lacks both "ice the stability and guidance required to ensure a safe and reliable cutting knife control in connection with high speed sewing and the like machines. The prior art arrangement has the further drawback that the adjustment of the cutting knife is subject to misalignment during use due to spring and other variable or yielding forces or adjustments inherent in the prior devices.

According to another arrangement known heretofore and utilizing a knuckle joint linkage as a motion transmitting means, the latter is adjusted between an operative and an inoperative position in its stretched or fully extended position by means of a manually operable control lever. In order to hold the knuckle joint in the extended position, a spring-loaded bolt is provided at the knuckle point near the end of one of the component arms or links, said bolt being urged into a recess in the op posite end of the cooperating arm or link of the joint. Buckling or angular adjustment of the joint is effected by means of a claw or the like having a handle and engaging the bolt rotatably coupling the component joint arms or links.

These and similar arrangements require the provision of a multiplicity of springs, stops and the like parts or elements, whereby to render it impossible to maintain an accurate adjustment or alignment of the motion-transmitting elements such as to ensure a safe and reliabe cutting knife control, especially in the case of fast running sewing and the like machines.

Accordingly, among the further objects of the present invention is the provision of a cutting knife or the like control mechanism of the general type referred to for use in connection sewing and the like machines which is both simple in design and efficient in ope-ration; which substantially consists of rigid component parts or elements, to ensure stability of both adjustment and operation; which requires a minimum of operating parts or elements; which will enable a control of the cutting knife or equivalent reciprocating member instantly and expeditiously; which will enable starting and stopping of the cutting knife simultaneously with its operation to and retraction from the operative or cutting position, respectively, by the aid of a single control or operating step; and which can be operated safely and reliably in connection with high speed sewing and the like machines or operating devices.

The invention, both as to its ancillary objects and novel aspects, will be better understood from the following detailed description taken in conjunction with the accompanying drawing forming part of this specification and wherein:

FIG. 1 is a partial perspective rear view of a conven tional sewing machine embodying an improved material cut-ting knife control mechanism constructed in accordance with the principles of the invention; and

FIG. 2 is a fractional representation shown on an enlarged scale and in partly exploded form, to more clearly illustrate the control device forming part of FIG. 1.

Like reference numerals denote like parts in both views of the drawing.

With the foregoing objects in view, the invention involves generally the provision of motion-transmitting and control mechanism connecting a continuously rotating drive shaft with a reciprocating driven member, such as the arm shaft and cut-ting knife, respectively, of a sewing machine, said mechanism in its preferred embodiment eoinprisin g" essentially a driving lever arm rotatable abdilfi'fikddhki andhavin'g oscillating motion imparted to it from said shaft through suitable motion transmitting means, such as an eccentric mounted upon said shaft and having an extension or eccentric rod rotatably connected to said arm. There is further provided a linkage mechanism connecting said iever arm with the cutting knife carrier or the like and comprising a first and a second link and a bolt having an eye at one end with one end of each of said links being 'rotatably mounted upon said bot; toromi'a knuckle'joincam 'wi'th'the'remairiing end or;saidfir r linlgrorambl connected 'to said oscillating arm andj withjthe rem ain'ing end 'of'saidfseoond 'link'ro' tatablyjconnected to said knifejor other driven member, to complete F the fniotion -transmittin'g path between said s'haft and saidmember. 'Ihe device -furtherfcompri'ses a manually operable'coritroi lever having a'fixed-pivot and arrange'd to slidably' engage' the ye" of'said bolt -Accordin'g"' to the invention, .t-he: eifectivedength of said 'drivingfor' oscillatinglevenis such as' to equal the efieetive Ieng't-hof "said-first knucklejointlink, whereby an' -angular'adjustme'nt' of said c'ontrol lever will enable the axis 'of 'said bolt 'orjoint to be'operated between two relative positions of coincidence iandnon-coincidence', respectivelwfof th'e joint" axis with the axis ot-said oscillating lever arm'.-' '[As a consequence, the operating stroke of"; the khife car 'erQor: equivalent driven member may be v'aried bet-weenzero andapredetermined value without interruption of the rotation of s'aid driven shaftwhile at thesame'time'retracting the knifea'wayfrom' the work in the inoperative or retracted position or position of coin cid'en'cewithe -knuckle joint axis with the axis of said oscillatingilever' arm; lnasmuch as' o'nly relatively rotatablel or linkage connections are utilized "by' the invention connecting or coupling th'e component elements of a the transmitting and control 'm'echanismflhat is,substantially free from: any yieldingpartsj or devices such as springs etc., there is ensured a maximtim of stability of both-the' adjustment" and operationof the'imotion. control and transmission 'r'n'echanisrn' between said rotary driving's'haft and reciprocatingdrivedmember; Y 1' Referring more particularly to the drawing, the numeral' l-iindicates' part of the cloth plate'and humeral 2 indicates part' ofi thetupper arm 'termina'ting in the head 3 of "a conventional sewing machinef Mounted npamhe arm oicdrive shaftz t, FIG: 2, ofthe machine iS an'eccent'ric-S serving asia driving" means'of th'ezniaterial cutting'knife' to: b'ei described presehtly,1said' eccentric i having I in turn niourited"thereonfa ringfl "from which extends an eccen-" tricrod'o'r'armfi "The latter'extend's through an opening 8'of dthe'armftinto' the interioriof ahousing 9;FIG. 1', whichisrattached to the rear of the-head 3 by the aid' of screwsrltforbyanyother suitable'nieans." t

Rotatablyiconnected tot-the endr'of the: eccentric r 6.1isithe 'armallfofqanangular lever 13 rotatable about a fixedpivot axis or shaft 12 andihaving'a second leverarm 14 iforming a right: angle with the arm 11*i'n theex-ample illustrated:' Rotatably connected mine end of'lever arm, 14 through a pin 15 is a first knuckle joint link: or'arrn l6zwhichzrtogether' with a second armx'orlink18.and a boitzorrpinrll *forms' 'a knuckle jointtconnectio'n or link agezwithronetendyofreach-of said links being' rotatably. mounted upomsaidibol-tin; the'manner showh and well understoodzfhe fre'eaend ofi thelinkt18' is, in turn, rotatably :connectedfthrough a further "link connection 23' to? the carrier or knife holder '11 whichzis motintedfor reciprocation adjacent to the needle or stitch forming tools-oflthe sewing machines .In' vthe example shown, the carrier 19 is guided in the vertical directionbyira: pair: OfEbOlfS or g'uide rods 20'- and- 21 being: attached to the head 3; ;the-::former; slidably "passing. through I a bore .andtheg latter passing -between :-th e-, "bifurcated ends. of said to-which.isattaehedqthe material cutting or trima mingv knifg zzqnz- Qwnsst to, 1., tr .e r' trest 'i bil s i pin-17 in a direction transverse thereto is a guide sleeve 24,

to form an eye bolt 25 or guideways at right angle to said bolt, through which is passed a cylindrical arm or guide bolt 26. The latter is pivotally mounted at one end by being fixedly connected to a shaft 27 rotatable about a stationary axis parallel to the axis 12 0f the oscillating lever 13. Control shaft 27 protrudes outwardly from the housing and carries a locking member or disc 28 being rigidly secured thereto in any suitable manner. Disc 28 is provided with an arcuate slot 31 which is engaged by an actuating pin or rod 32 secured to a control member or cam disc 33 being freely rotatably mounted upon theouter end ofthe shaft '27 in a position parallel ,to Ithetlocking disc 2.1'Thc circumference of member 33 is formed with a camming surface 34 which is engageds by a spring loaded control rod SSVrigidlysecured to and extending transversely-from a pawl 37 -rotatable about afixed'axis 36 and having a nose 38 adapted to engage either'of a pair of'notches or'depressions 29 and Si) in the member 28." A flatspr ing'39 resting with one end against a fixed abutment or pin 40 serves to resilientlyfur'ge'therod 3Sfagainst the'cam surface'34 of the control member 33.' :The actuating rod 32 engaging th'e'Slbt 31 to form a lost motio'n connection with the member 2 8 'h'as its outerend 41 protruding beyond the member '33" rotatably connected to an intermediate lever arm 4 2 which is in turn rotatably connected at'45' to a control arm or lever 44 rotatable about a fixed shaft or axis '43 and carrying alcontrol knob or the like as shown In operating the cutting device described hereinbe'fore, the fre'egend of the control lever 44 is operated in an upward or clockwise direction, whereby to cause the actuating rod 32.to rotate member 33in the same direction about eme 2']. As a result of the shape of the cam 34, the rod '35 being attached to the pawl 37 and resilientlyengaging said cam will bejoperated to aposition whereihjthle nose 33 of the pawl 371is released from the notchjfitlofthe member 28. Asa consequence, control shaft 27 is now free to rotate. During this initial operation jo'f the' contfol leyer 44, the actuating rod 32 has been displaced to a position such as to abut against the lower inner end 'of thel'slot 31 in the member 28.

As-.the rotation of the control lever 44 is continued,

' member28cwitl berotated byfollowing the movement oflthelactuatingt rod 32,-:whei'eby. to, rotate the control shaft. 27 connected to the. :member .28- in a clockwise directioin. ,LAftenmember 28 has reacheda position Where the notch isiopposite some fnosci 38 of the pawl 37, spring "3 9 causes .the pawl to again lock the member 28 asa result of thelshape-of thecam surface 34 of the member 33.!fAs.ajconsequenca'the control shaft27 will again be locked, as at'tbe beginning ,of the control 7 operationh sjf'cfj 7' c t I i During ltherotationofithe shaft 27.through an angular distance determined by the distanceof' thej-notche s 29 and of the, member 28,.asimilar rotation or deflection hasibeen impar'tedsto ctheguide bolt 26, insuch a manner asto. causeloperatio'nIofvthe vaxisof the bolt 17 'of the knuckle joinhfrorr'i its. operative position shown in the drawing to an" inoperative,,position.with the axis ofthe joint or boltlls'lfcoiriciding swith the axis 12 of the oscil lating' leverr'll'v. ,Inthis, position, no movement is trans mitt'ed to" the knuckle joint by the eccentric 5 or oscillating, 1ever1 3, .thus effectinga stoppage of the operation of the knif e 22,while atthe same time raising the knife through, its, ,carrier, 22,'to an inoperative-position spacedj The same, operation takes ,placein' a reverse order by g the control arm in a downward orcounterclocks ition substantially withouttinterruption of therotation of ithe W driving shaft 4, in a mannerreadily understood, from the foregoing.

irectiomif'asa result oftheshape of the camming, surface,,34, in, order toretur-n the device .torop'erative po-- In the foregoing the invention has been described with reference to a specific operative device. It will be evident, however, that variations and modifications, as well as the substitution of equivalent parts or elements for those shown herein for illustration, may be made in accordance with the broader purview and spirit of the invention as set forth in the appended claims. The specification and drawing are accordingly to be regarded in an illustrative rather than in a restrictive sense.

We claim:

1. The combination with a sewing machine having a rotating drive shaft, a reciprocating carrier and a material cutting knife attached to said carrier, operating mechanism for said knife comprising a lever arm having a fixed pivot axis, motion-transmitting means between said shaft and said arm to oscillate said arm about said axis, linkage means connecting said arm with said carrier comprising a first and a second link and a bolt with means to provide a guideway at a right angle thereto, one end of each of said links being rotatably mounted upon said bolt, to form a knuckle joint, means rotatably connecting the remaining end of said first link to the end of said arm, further means rotatably connecting the remaining end of said second link to said carrier, the effective length of said first link being equal to the effective length of said arm, a control lever having a fixed control shaft and slidably engaging said guideway, and means to operate said control lever between two relative positions of coincidence and non-coincidence, respectively, of said first pivot axis and the axis of said joint.

2. In a sewing machine as claimed in claim 1, said motion-transmitting means comprising a further lever arm rigid with said first flllll, an eccentric mounted upon said shaft and having an eccentric rod and means rotatably connecting the end of said rod to said further lever arm.

3. In a sewing machine as claimed in claim 1, said motion-transmitting means comprising a further lever arm rigid with and forming an angle with said first arm, and an eccentric mounted upon said shaft and having an eccentric rod rotatably connected to said further lever arm.

4. In a sewing machine as claimed in claim 1, said last means being comprised of a locking member connected to said control shaft and having a pair of spaced notches, a spring-loaded stationary pawl adapted to engage said notches, to lock said control shaft against rotation, and manually operable control means coupled with said member through a lost motion connection to initially release said pawl from said member and to afford operation of said member between two angular adjusting positions with said pawl engaging either of said notches, respectively.

5. The combination with a sewing machine having a rotating drive shaft, a reciprocating carrier, a material cutting knife attached to said carrier, operating mechanism for said knife comprising a lever arm having a fixed pivot axis, motion-transmitting means between said shaft and said arm to oscillate said arm about said axis, linkage means connecting said arm with said carrier comprising a first and a second link, a bolt, a sleeve transverse to and connected to one end of said bolt, one end of each of said links being rotatably mounted upon said bolt, to form a knuckle joint, means rotatably connecting the remaining end of said first link to the free end of said arm, further means rotatably connecting the remaining end of said second link to said carrier, the effective length of said first link being equal to the effective length of said lever arm, a rotatable control shaft having a fixed axis parallel to said pivot axis, an arm extending transversely from said control shaft and slidably engaging said sleeve, for displacing the axis of said joint between a position of coincidence and a position of non-coincidence, respectively, with said first pivot axis by operation of said control shaft.

6. In a sewing machine as claimed in claim 5, said motion-transmitting means comprising a further lever arm rigid with said first arm, an eccentric mounted upon said shaft and having an eccentric rod, and means rotatably connecting the end of said rod to the end of said further lever arm.

7. In a sewing machine as claimed in claim 5, said motion-transmitting means comprising a further lever arm rigid with and forming a right angle with said first arm, and an eccentric mounted upon said shaft and having an eccentric rod rotatably connected to said first lever arm.

8. In a sewing machine as claimed in claim 5, said last means being comprised of a locking member connected to said control shaft and having a pair of notches spaced from one another, a spring-loaded stationary pawl adapted to engage said notches, to lock said control shaft against rotation, and manually operable control means coupled with said member through a lost motion connection, to initially release said pawl from said notches, whereby to afford operation of said member between two angular adjusting positions with said pawl engaging either of said notches, respectively.

9. In combination with a rotating drive shaft and a reciprocating driven member, operating mechanism comprising a lever arm having a fixed pivot axis, motion-transmitting means between said shaft and said arm to oscillate said arm about said axis, linkage means between said arm and said member comprising a first and a second link and a bolt with means to provide a guideway at a right angle thereto, one end of each of said links being rotatably mounted upon said bolt, to form a knuckle joint, means rotatably connecting the remaining end of said first link to said arm, further means rotatably connecting the remaining end of said second link to said member, the effective length of said first link being equal to the effective length of said arm, a rotatable control shaft parallel to said first pivot axis, and an arm extending transversely from said control shaft and slidably engaging the guideway of said bolt.

10. In a device as claimed in claim 9, said motiontransmitting means being comprised of a further lever arm rigid with said first arm, and an eccentric mounted upon said shaft and having an eccentric rod rotatably connected to the end of said further lever arm.

11. In a device as claimed in claim 9, said motiontransmitting means being comprised of a further lever arm rigid and forming a right angle with said first lever arm, and an eccentric mounted upon said shaft and having an eccentric rod rotatably connected to said further lever arm.

12. In a device as claimed in claim 9, including adjusting means comprising a locking member connected to said control shaft and having a pair of notches spaced from one another, a spring-loaded stationary pawl adapted to engage said notches, to lock said control shaft against rotation, and manually operable control means coupled with said locking member through a lost motion con nection, further means operably connecting said last means with said pawl to initially release said pawl from said member and to afford rotation of said control shaft between two angular adjusting positions with said pawl engaging either of said notches, respectively.

13. In a device as claimed in claim 12, said notches being spaced and positioned upon said member to define two relative adjusting positions of coincidence and noncoincidence, respectively, of the axis of said joint with said first pivot axis.

14. In combination with a rotating drive shaft and a reciprocating driven member, operating mechanism comprising a lever arm having a first fixed pivot axis, motiontransmitting means between said shaft and said arm to oscillate said arm about said axis, linkage means connecting said arm with said member comprising a first and a second link and a bolt, one end of each of said links being rotatably mounted upon said bolt, to form a knuckle joint, means rotatably connecting the remaining end of said first link to the end of said arm, further means rotatably connecting the remaining end of said second link to said member, the length of said arm being substan- 

1. THE COMBINATION WITH A SEWING MACHINE HAVING A ROTATING DRIVE SHAFT, A RECIPROCATING CARRIER AND A MATERIAL CUTTING KNIFE ATTACHED TO SAID CARRIER, OPERATING MECHANISM FOR SAID KNIFE COMPRISING A LEVER ARM HAVING A FIXED PIVOT AXIS, MOTION-TRANSMITTING MEANS BETWEEN SAID SHAFT AND SAID ARM TO OSCILLATE SAID ARM ABOUT SAID AXIS, LINKAGE MEANS CONNECTING SAID ARM WITH SAID CARRIER COMPRISING A FIRST AND A SECOND LINK AND A BOLT WITH MEANS TO PROVIDE A GUIDEWAY AT A RIGHT ANGLE THERETO, ONE END OF EACH OF SAID LINKS BEING ROTATABLE MOUNTED UPON SAID BOLT, TO FORM A KNUCKLE JOINT, MEANS ROTATABLY CONNECTING THE REMAINING END OF SAID FIRST LINK TO THE END OF SAID ARM, FURTHER MEANS ROTATABLY CONNECTING THE REMAINING END OF SAID SECOND LINK TO SAID CARRIER, THE EFFECTIVE LENGTH OF SAID FIRST LINK BEING EQUAL TO THE EFFECTIVE LENGTH OF SAID ARM, A CONTROL LEVER HAVING A FIXED CONTROL SHAFT AND SLIDABLY ENGAGING SAID GUIDEWAY, AND MEANS TO OPERATE SAID CONTROL LEVER BETWEEN TWO RELATIVE POSITIONS OF COINCIDENCE AND NON-COINCIDENCE, RESPECTIVELY, OF SAID FIRST PIVOT AXIS AND THE AXIS OF SAID JOINT. 